Rheostat



J. PARKIN, JR.

RHEOS TAT.

APPLICATION FILED APR- 25,1921.

HHHI IIHHHH WITNESS Patented Aug. 1, 1922.

IN V EN TOR Jam Fur/mg JR.

UNITED STATES PATENT omcs.

JOHN PABIIN, 33., 0] SAN RAFAEL, GALIIOBNIA,

BHEOSTAT.

To (all whom it may concern:

Be it known that I, JOHN PARKIN, Jr., a citizen of the United States, and a resident of San Rafael, Marin County, State'of California, have invented a new and useful Rheostat, of which the following is a specification.

My invention relates to devices for varying the resistance in an electric circuit, and one of the objects of the invention is to provide a variable resistance device comprising few parts of very simple construction, and having a graduated dial to permit close adjustment of the resistance. Another object is the provision of a variable resistance device of the dial type, practically all of which lies in front of the panel on which it is mounted, leaving the rear of the panel free. Another object is the provision of a dial type rheosta-t which is very easy to in stall.

My invention possesses other objects and features of advantage, some of which, with the foregoing, will be set forth in the fol lowing description of my invention. It is to be understood that I do not limit myself to the showing made by the said description,

, as I ma adopt variant forms of my invention wit in the scope of the claims.

In the drawings, Fig. 1 is a side elevation, largely in section, of one of my rheostats mounted on ,a panel. Fig. 2 is a rear view of the graduated disk or dial. Fig. 3 is a' front elevation of my rheostat,

My rheostat com-prises a knob 2 of bakelite or other non-conducting material molded about the core orcenter 3, preferably of brax, and threaded to receive the screw 4, which acts as the shaft upon which the device is mounted. The periphery of the knob is knurled to permit of its digital control. At the base of the knob and concentric therewithis the graduated disk or dial 5 also preferably of bakelite, fixed for rotation with the knob and shaft 4 by the nut 6 threaded on the shaft.

A flan d bushing 7 is fixed in the panel 8 and he d therein by the'nut 9 threaded on the bushing at the rear of the panel. The shaft 4comprisesa screw, the head of which engages the rear end of the bushin The rts are assembled in the relation 5 own in g. 1 and the screw shaft 4 turned in firmly.- The nut 6 is then turned suflicihntly to free Specification 01 mm; 1mm. t t 1, 192

Application illed April 25,

1921; Serial No. 4,142.

itself from the bushin 7 and still tighter to bind the graduated disk to the knob The disk 5 is beveled on its periphery, the beveled edge being provided with graduations '11 so that the amount of resistance in the clrcuit may be visually evaluated. An in-' point 12 is fixed in the panel for ready de'x reading "of the dial.

The rear or under surface of the dial near its periphe in which a elical coil of resistance wire isdisposed. The groove-extends intothe body of the disk' and inwardly toward its center of rotation so that the resilience in the coil of resistance wire will tend to retain the coil in the groove. One end 14 of the wire of the coil is hooked through an aperture through the flange 16 which forms the inner boundary of the groove 13 and the other end 17 of the resistance coil is carried toward the, center of the disk and caught under the nut 6, with which it forms an electrical contact. Therefore the resistance coil is electiically connected to the conductor 18 forming one side of the circuit in which the rheostat is used, and connected to the nut 9.

Fixed to the panel 8 by bolts 19 is a spring contact arm 21 arranged to resiliently engage the coils of the resistance element as shown in Fig. 1. A conductor 22, forming the other side of the circuit in which the rhcostat is used is electricall connected to one of the bolts 19. For-me on the under ,surfaceof the flange 16, either by a pin set in the material of the flange or by an into-- gral extension of the flange is a stop 23" ingthe dial to the right the circuit is closed and. a decreasing amount of the resistance wire is thrown into the circuit until the minimumis reached upon a full revolution of the knob.

I claim:

1. A variable resistance device [coin rails; a variable resistance element circularly dis:

ing a. rotatably mounted graduated is provided with a groove 13 po sed about said disk and fixed for rotation therewith, and a knob for the digital control of said disk.

2. A variable resistance device com rising a rotatably mounted graduated isk, a variable resistance element circularly disposed about said disk and fixed for rotation therewith, and a knob for the digital control of said disk fix d thereon.

3. A variable resistance device comprising a rotatably mounted knob, a raduated disk fixed concentrically on sai knob, a variable resistance element circularly disposed about said disk and fixed for rotation therewith, a conductor on said disk for connecting said element to one side of a circuit, and a conductor 'slidably engaging said element for connecting it with the other side of said" circuit.

4. "A variable resistance device comprising a rotatably mounted knob, a graduated disk having an annular groove therein and fixed concentrically on said knob, a variable resistance element disposed in said groove, a conductor on said disk 'for connecting said element to one side of a circuit, and a conductor slidably engaging said element for connecting it with the other side of said circuit.

5. A variable resistance device comprising a rotatably mounted shaft of conduct-.

ing material, a knob of non-conductin material fixed on said shaft, a graduate dial fixed at the base of said knob for rotation therewith, a-helical coil of resistance wire circularly disposed about said knob and having one of its ends connected to said shaft, a conductor adjacent said knob and slidably engaging said coil, and a conductor slidably engaging said shaft.

F 6. A var1able resistance device comprising a panel of non-conducting material, a shaft of conducting material rotatably mounted in said panel, a graduated disk hav- 111g an annular groove therein fixed on saidshaft, a variable resistance element dis osed in said groove and connected at one en with said shaft, a digitally controlled knob fixed on said disk, an arm of conducting material fixed on said panel and resiliently engaging said element, a plate of conducting material on the rear of said panel electrically connected to said shaft, and a spring interposed between said shaft and said plate.

7. A variable resistance device comprising a rotatably mounted graduated disk having an annular groove in the under side thereof, a variable resistance element dis posed in said groove,.and a knob fixed on said disk for its digital control-..

8. A variable resistance device com rising a rotatably mounted graduated disk aving an inwardly sloping annular groove in the under side thereof, a resilient variable resistance element disposed in said groove,

and a knob fixed on said disk for its digital control.

In testimony whereof, I have hereunto set my hand.

' JOHN/PARKIN, JR. 

